The present invention relates to a pneumatic tire, more particularly to a motorcycle tire having a tread pattern suitable for running on rough terrain and capable of improving cornering performance and traction performance during straight running.
Motorcycle tires designed for use in motocross race and the like are usually provided in the tread portion with crown blocks disposed on the tire equator, shoulder blocks disposed along the tread edges and middle blocks therebetween so that the tread blocks dig into soft ground such as sandy and muddy areas to improve the traction performance and cornering performance.
In order to improve the cornering performance of such motorcycle tire, in Japanese Patent Application Publication No. 2-74405, axially outside corners of middle blocks are chamfered so that axially inside edges of shoulder blocks located on the axially outside thereof are improved in the ground contact and thereby the cornering performance is improved.
In Japanese Patent Application Publication No. 6-320916, axially inside corners of middle blocks are stepped so that the steps provides additional edges which can contact with the ground during cornering and thereby can improve the cornering performance.
In the techniques described in the above-mentioned publications, however, the effect to improve the cornering performance essentially depends on the edges of the tread blocks. Accordingly, when the edges are worn away, the effect to improve the cornering performance also fades away.